Feeding mechanism for grinding wheel truing apparatus



June 4, 1940. WOOD 2,203,608

FEEDING MECHANISM FOR GRINDING WHEEL TRUING"APPARATUS Original Filed May 4, 193B 3 Sheets-Sheet l :(moenfor WALLACE H. W001:

aitorneg w. H. WOOD June 4,' 1940.

FEEDING MECHANISM FOR GRINDING WHEEL TRUING AliARATUS 3 Sheets-Sheet 2 Original Filed lday l, 1938 58 56 WALLACE H, W001: H E B Gttorneg June 4, 1940. w, WQQD 2,203,608

FEEDING MECHANISM FOR GRINDING WHEEL TRUING APPARATUS Original Filed May 4, 1938 3 Sheets-Sheet I5 109 i I I8 11 45 4 106 7/9 I32 I I Inventor WALLACE H. W002 q'l-uaa A attorneg II The invention accordingly consists in the feamounted on the upper surface of the wheel slide 15 UNITED STATES PATENT. OFFlCE FEEDING MECHANISM FOR GRINDING l WHEEL TRUING APPARATUS WalIace H. Wood, Worcester, Mass" asslgnol' to Norton Company, Worcester, Mass., a corner:- tion of Massachusetts Original application May 4, 1938, Serial No. 206,027. Divided andthis application January 4, 1939, Serial n puazss v 2 Claims. (0114-526) I The invention relates to grinding machines, enlarged scale, taken approximatelyon the line 7 and more particularly to a tool feeding mechal2l2 of Fig.9; nism therefor This application is a division of Fig. 13 is a cross sectional view, taken approxiapplication Serial No. 206,027 filed May 4, 1938. mately on the line. l3-,-l3 of Fig. 12; and One object of, the invention is to provide a Fig. i4 is a fragmentary sectional view, taken 5 simple and thoroughly practical tool feeding approximately on the line li -l4 of Fig. 9. mechanism for a tool feeding mechanism. An- The improved truing apparatus has been illusother object of the invention is to provide an trated in the drawings as mounted fixedly on top improved pawl and ratchet tool feeding mechaof a wheel slide Ill which rotatably supports a nism. Another object of the invention is to wheel spindle ll carrying aplurality of grinding 10 provide an improvedhydraulically operated pawl wheels l2 and I3 of the same or different sizes and ratchet mechanism for actuating a feed or diameters. The grinding wheel spindle ll screw. Other objects will be in part obvious may be driven in anysuitable manner, such as a or in part pointed out hereinafter. motor drive in which an electric motor I4 is tures ofconstruction. combinations of elements, III. The motor is provided witha driving pulley and arrangements of parts; as will be exemplified I5 which is of the multiple V-groove type and in the structure to be hereinafter described, and transmits power by means of multiple V-belts the scope of theapplication of which will be in- IE to a multi-grooved pulley ll mounted on the l dicated in the following claims. outer end of the wheel spindle ll. 20

In the accompanying drawings, in which is The wheel slide l0 supports a frame or base shown one of various possible embodiments of IS of the truing apparatus. An adjustable horithe mechanical features of this invention, zontally arranged member I9 is pivotally con- Fig. 1 is a front elevation of the improved trunected by a stud 20 with the frame l8. An ading apparatus mounted on a wheel slide having justing screw 2i threaded into a lug 22 project- 25 the wheel guard removed; I ing from the base It serves to adjust the member Fig. 2 is a right-hand end elevation of the I9 about its stud or pivot 20 to facilitate adjustimproved truing apparatus, showing the wheel ment of the positon of the member l9 relative slide and the wheel driving motor; to the base l8. A look nut'serves to lock the Fig. 3 is a rear elevation of the improved truscrew 2| in adjusted position. The member I9 30 ing apparatus; may be clamped in adjusted position on they Fig. 4 is a plan view of the truing apparatus. frame l8 by means of clamping screws 25 which Fig. 5 is a hydraulic piping diagram showing pass through elongated slots 26 in the lugs 21 the truing tool traversing and feeding mechaon the frame I8 and are screwthreadedinto the 5 nism; member IS. A dovetailed slideway 30 is formed Fig, 6 is a cross-sectional view, on an enlarged integral with the member 19 and is arranged to scale, taken approximately on the line 66 of support a horizontally movable slide 3| having Fig. 1, showing the cam for causing a vertical a dovetailed surface 32 which mates with the movement of the truing tool and also the hydovetailed slideway 30. An adjustable tapered draulic truing tool traverse cylinder and assogib 33, interposed between the dovetailed ways 40 m t d parts; i 30 and 32, serves to take up lost motion between- Fig. 7 is a fragmentary vertical sectional view, the fixed and movable parts of the slide. A screw taken approximately on the line l-l of Fig. l; v 34 is provided to facilitate endwise adjustment Fig. 8 is a cross sectional view, on an enlarged of the gib 33. l scale, taken approximately on the line 8--8 of. The horizontal slide 3| is provided with a ver-- 45 Fi 1; tically arranged member 28 which is formed in- Fig. 9 is a fragmentary front elevation, on an tegral therewith or fixedly mounted thereto. enlarged scale, of the truing tool feeding mecha- The vertically extending portion 35 on the horinism, having parts' broken away more clearly zontal slide 3| is provided with-adovetailed to show the construction; slideway 36 which supportsa vertically movable 50 Fig. 10 is a fragmentary sectional view through slide 31 having a mating dovetailed way 38. An the feed pawls; adjustable tapered gib 39 serves to take up lost Fig. 11 is a fragmentary plan view of the feed motion between the dovetailed slideways 36 and pawls as shown in Fig. 10; g 38, and a screw 40 serves to facilitate adjustment Fig. 12 is a fragmentary sectional view, on an of the gib 39.. r 55 "A second vcrticaly arranged slide 4| is supported by a dovetailed slideway 42 formed inlegral with the vertically extending member 35. The dovetailed slideway 42 is provided with an adjustable tapered gib 43 having a screw adjustment 44. The slide 4| is preferably arranged so that-.it inaybe moved vertically during the horizontal movement of the slide 3|.

The vertical slide 31 adjustably supports a truing tool holder which in the present case is formed as a cylindrical bar 45 which is .slidably keyed within an aperture 46 formed in a projection 41 of the slide 31. The truing tool holder or bar 45 is arranged to be clamped in adjusted position within the aperture 46 in the projection 41 of the slide 31 by binding screws 48 and 49. The truing tool support 45 carries at its outer end a truing tool 50 having a diamond point 5| ar-v ranged for successively truing the peripheral surfaces of the grinding wheels I2 and il3.

The slide 4| is preferably adjustably'connected to the slide 31 so that during the traversing movement of the horizontal slide 3|, the vertical slides 31 and 4| are moved together in a vertical direction to control the path of movement of the diamond or truing tool-5|.

A vertically extending feed screw 53 is rotatably connected to the lug 52 and extends downwardly through a nut (not shown) which is carried by or formed integral with the slide 31. .The lower end of the screw 53 is journalled in and slidably keyed within aspiral gear 55 which meshes with a spiral gear 55 formed on the inner end of a rotatable shaft 51. The shaft 51 is journallcd in bearings 58 within the casing and is provided at its outer end with a manually operable hand wheel 59. By adjustment of the wheel 59, the feed screw 53 may be rotated to adjust the position of the slide 31 relative to the vertically movable slide 4|.

A power operated traversing mechanism is provided for producing a longitudinal traversing or reciprocating movement of the horizontally movable slide 3| to traverse the truing tool 5| relative to the periphery of the grinding wheels l2 and I3. In the preferred form a fluid pressure traversing or reciprocating mechanism is provided comprising a cylinder 68 which is formed within the member l9. A piston 6| is slidably mounted within the cylinder 68 and is connected] to one end of a piston rod 62, the other end of which is fastened by nuts 63 to an end cap 64 formed integral with or fixedly mounted on the end of the horizontally movable slide 3|.

A fluid pressure system is provided to convey fluid under pressure to the cylinder 68. This system may comprise a reservoir 63 which is preferably located within the base of the machine. Fluid is pumped from the reservoir 63 through a pipe 64 by means of a pump 65 which is preferably a motor driven fluid pressure pump of a standard well known type. Fluid under pressure from the pump 65 passes through a pipe 66, a portion of which is flexible hose, to a control valve 61. A pressure relief valve 68 is connected with the pressure pipe 66 by a short pipe 69 and serves to relieve excess pressure in the system and return it to the reservoir 63 through a pipe I8.

. The control valve 61 is preferably a. piston type valve and is arranged to control the admission and exhaust of fluid to and from the truing tool traverse cylinder 68 and also'to control the admission of fluid to a truing tool feed mechanism to be hereinafter described.

The slide 4| is providcd with a forwardly projecting boss or lug 52.

. The control valve 61 is provided with a valve stem 15 having formed integrally therewith a plurality of valve pistons 16, l1, l8 and I9. Fluid under pressure passing through the pipe 66 enters a chamber between the valve pistons I6 and,

I1 and passes out through a pipe or passage 8| into a cylinder chamber 82 at the left-hand end of the cylinder 68 (Fig. 5) .to move the piston 6| toward the right, which serves also to move the horizontal slide 3| and the truing tool 5| toward the right to its extreme right-hand position, as indicated in Figs. 1 and 5. During the movement of the piston 6| toward the right, fluid within a cylinder chamber 83 exhausts through a pipe or passage 84 into a valve chamber 85 located between the valve pistons I1 and I8 and out through a pipe or passage 86 into the reservoir 63. Similarly, when the valve stem 15 is shifted toward the right (Fig. 5), fluid under pressure from the pipe 66 passes through pipe 66a into the valve chamber 85 between the valve pistons 11 and 18 and passes through the pipe or passage 84 into the cylinder chamber 83 to cause the piston 6| to move toward the left and also moving the slide 3| and the truing tool 50 toward the left. During this movement, fluid within the cylinder chamber 82 passes out through the pipe 8| into thecylinder chamber 68 between the valve pistons 16 and I1 and out through the pipe or passage 86 to the exhaust.

A speed control mechanism is provided to control the speed of movement of the truing tool both during its idle stroke and during the traverse of the diamond 5| across the peripheries of the grinding wheels i2 and I3. It is desirable to provide a control valve mechanism in the exhaust pipe line or passage 86 so that the truing tool will traverse at a rapid rate during the idle stroke of the diamond 5| and will be automatically slowed down to a proper truing speed when the diamond 5| moves into operative truing engagement with the peripheries of the wheels l2 and I3. A speed control valve 98 of the piston type is connected at one end of the pipe line 86. The valve 90 is a piston type valve having a pair of valve pistons 9| and 92. Fluid exhausting through the pipe 86 enters a valve chamber 93 between the valve pistons 9| and 92 and in the position shown in Fig. 5 passes out through a port 94 and a pipe 95, a portion of which is flexible'hose, to the reservoir 53. In the position of the valve 98 (Fig. 5), unrestricted exhaust of fluid from the pipe 86 passes out through the pipe 95 so that the piston 6| and slide 3| together with the diamond 5| will traverse at a maximum speed.

The valve pistons 9| and 92 are normally urged in a downward direction by means of a spring 96. The lower end of the valve piston 92 is provided with a conical end portion 91 which rides upon an adjustable cam 98. The cam 98 is held 'in a relatively fixed position and is supported on the horizontally movable slide 3|. The controlvalve 61 and the speed control valve 98 are supported by the fixed member Hi. When the slide 3| traverses toward the left (Figs. 1 and 5), the slide will travel at a rapid rate until the conical end 91 rides into a low portion 98a on the cam 98. The forward movement of the valve pistons 9| and 92 (Fig, 5) serves to close the port 94, after which fluid within the pipe 86 exhausts through a needle valve 99 and into the pipe 95 into the reservoir 63. By manipulating the needle valve 99, the speed of movement of the truing tool 5| during its truing traverse across the face of the grinding wheels I2 and I3 may be regulated as desired. It will be readily apparent from the foregoing disclosure that when the valve pistons 9I and 92 are in a rearward position (Fig. the port 98 is wide open, allowing unrestricted exhaust of fluid to allow the truing tool slide 3I to traverse at a maximum speed, and upon closing of the port 94 fluid must thereafter exhaust through the needle valve 99 to allow the traverse to continue at a slow truing speed. In truing a pair of spaced wheels I2 and I3, such as shown in Fig. 1, the cam 98 is arranged so that the grinding tool 58 will travel at a rapid rate until the diamond 5| is about to engage the periphery of the wheel I2, after which thetruing tool 58 I travels at a slow truing speed. When the truing tool 58 leaves the wheel I2, due to a raised portion 98b on the cam 98, the traverse will resume a rapid idle traverse until the diamond 5I-is about to engage the periphery of the wheel I3, at which time the control valve 98 again moves forwardly as the cone-shaped follower 98 rides ing the shape of the cam 98, the speed of the truing tool 58 may be readily controlled for truing either a pair of wheels, as shown in the drawings, or any other arrangement, such as a single wide faced wheel or a multiplicity of I wheels arranged in spaced relationship on the end of the spindle I I. The cam 98 is provided with elongated slots I88 and I8I through which clamping T-bolts I82 and I83 pass adjustably to secure the cam 98 onto an upwardly extending in the bearings II8 and III.

projection I84 of the horizontal slide 3|.

In truing a grinding wheel or a plurality of grinding wheels arranged in spaced relationship with each other, it isdesirable to reciprocate the truing tool across the peripheral surface of the wheel either one or more reciprocations for each truing operation. In the disclosure in the drawings, a mechanism has been illustrated for controlling the valve81 so that the truing tool 58 may reciprocate continuously as many times as the operator desires.

A reversing mechanism is provided for automatically actuating the reversing or control valve 61 to control the continuous reciprocation of the truing tool 58. A pair of adjustable dogs I85 and I88 are adjustably supported by a, T-slot I8'I formed in a projection of the slide 3|. A reversing lever I88 is supported on a vertically arranged rock shaft I88 which is journalled in bearings H8 and III which are supported on the fixed member I 9. The rod I 89 is rotatably supported A lost motion connection is provided between the rod I89 and the valve stem I5. A lever II 2 is rotatably supported by the upper end of the rod I89 and carries a pin II 3 at its upper end which rides in a groove in I the spool-shaped member I I4 which is formed in.

tegral with or fixedly mounted on the outer end of the stem 15. The lever I I2 is free to rotate relative to the shaft l89.. A member I I5 is keyed to rotate with the shaft I 89 and is provided with two oppositely extending arms H6 and III each of which is provided with an adjustable stop screw 8 and H9, respectively. The lever H2 is provided with two projecting arms I28 and HI which are arranged in the path of the stop screws H8 and H9. When the shaft I89 is rocked to reverse the valve 81, the member H5 rocks until the lost motion is taken up before the lever II2 starts to move to shift the reversing valve 81. By manipulation of the screws H8 and H9, the extent of lost motion between the member II 5 and the lever II2 may be varied as desired.

A suitable load and fire mechanism is provided for controlling the shifting movement of the control valve 81. A roller I25 is supported by a stud I28 fixedly mounted on the bracket III on the fixed member I9. An arm I2! is fixedly keyed to the lower end of the shaft I89 and serves as a support for a spring-pressed arrow-pointed plunger I28 which cooperates with the roller I25 and serves as a load and fire mechanism to control the reversal of the valve 81.

The reversing lever I88 is preferably pivotally supported by a stud I38. The stud I38 is supported by a member I3I which is rigidly clamped onto the vertical shaft I89. The reversing lever I88 is provided witha forwardly projecting, manually operable lever I32 by means of which the mechanism may be manually controlled. By raising the control lever I32 to the dotted position I3 2a (Fig. 6), the reversing lever I88 may be dropped out of the path of the reversing dogs I85 and I88 to allow the slide 3| to move to its extreme right-hand position, as illustrated in Fig. 1, withthe piston 8| bearing against the end of the cylinder 88.

When it is desired to start the truing operation, the operator manually rocks the lever I32 in a clockwise direction (Fig. 4) which serves to shift the valve stem I5 of the control valve 81 toward the right (Fig. 5) to start the movement of the piston 6| toward the left to cause acorresponding movement of the truing tool 58. Due to the angled-off surface on the under side of the dog I85, the lever I32 will swing into position I320, and then drop into an operating position so that the reverse lever I88 lies in the path of the reversing dogs I85 and I88. The reciprocation of the truing tool 58 and its supporting slide 3I continues until the wheels I2 and I3 have been trued to the desired extent, at which time the operator raises the control lever I32 into position I32a to allow the slide 3| to traverse to an inoperative position toward the right, as shown in Fig. 1. I

In order that the truing tool 58 may true a plurality of spaced grinding wheels of different diameters,- such as a pair of spaced grinding wheels I2 and I3, respectively, it is desirable to provide a control mechanism to move the slides 31 and II in timed relation with the traversing or reciprocating movement of the horizontal slide 3i so that a single truing tool 58 may be utilized to true both wheels, that is, so that the diamond 5i may pass across the periphery of the wheel I2 and then the slides 31 and II may be moved into a second predetermined position to true the periphery of the grinding wheel I3. Due to the short space between the two grinding wheels and due to the difference in their diameters, it is not feasible to utilize a fixed cam bar for this purpose. To overcome this clifllculty, a rotatable cam I58 is provided to transmit a. vertical motion to the slides 31 and 4|, which movement is controlled by the longitudinal traversing movement of the truing tool 58 and the horizontal slide 3|. 'I'he rotatable cam I58 is supported on a shaft I5I which is supported on the vertical member 35 which is integral with thehorizontal slide 3| The outer end of the shaft II is clamped. and supported in a bearing I52 formed integral with a bracket I53 which straddles the slide I and is fixedly mounted on the vertical member 35. A follower I5 is fixedly mounted on the vertically movable slide 4| and is arranged to engage the periphery of the rotatable cam I50.

In order to transmit the desired vertical movement to the truing tool 50 and its supporting slide 31 in timed relation with the traversing movement of the horizontal slide 3|, a rack bar I55 is fixedly mounted on'themember I9. A gear I56, either formed integral with or connected to rotate with the cam I50, meshes with the rack I55 and transmits a rotary motion to the cam I50 as the shaft supporting the cam is moved longitudinally during the traversing movement of the slide 3| and the truing tool 50. The cam I50 is preferably designed to give the desired vertical movement to the truing tool 50 and, as illustrated,

comprises two concentric portlonsfor holding the truing tool 50 against vertical movement during the interval in which it traverses across the periphery of the wheel, and the connecting portions between the two concentric surfaces are shaped to give a'predetermined lift or drop to the truing tool 50 and its supporting slides 31 and 4| so that the diamond 5| may be readily moved after truing the larger diameter wheel I2 down to a position to true the smaller diameter wheel I3 and vice versa when the slide 3| is traversed in the reverse direction.

In order to attain one object of the invention, an automatic feeding mechanism is provided for feeding the diamond 5| and truing tool 50 and its supporting slide 31 downwardly at each end of the reciprocatory stroke of the slide 3|, so that the truing tool 50 will cut a fresh path across the wheel periphery. In the preferred construction, an hydraulically actuated pawl and ratchet mechanism is provided incrementally to rotate the feed screw 53 at each end of the longitudinal traversing stroke of the slide 3| to reposition the truing tool 50 for the next traversing movement. A sleeve I60 is rotatably supported on-a reduced portion IGI of the shaft 51. The sleeve I60 has formed integrally therewith an outwardly ex-' tending arm I62 having a gear segment I 63 formed at its outer end. Thegear segment I63 meshes with a slidably mounted rack I64 formed adjacent to one end of a piston rod I65 having an integral piston I66 fixed at its right-hand end (Fig. 5). The piston I66 is slidably mounted within a fluid pressure cylinder I61. A spring I68 surrounding the piston rod I65 and interposed between'the piston I66 and a shoulder I69 within a casing I serves normally to urge the piston I66 in a direction toward the right (Fig. 5) When fluid under pressure is admitted through a pipe III into a cylinder chamber I12, the piston I66 is moved toward the left (Fig. 5) against the compression of the springl68 to move the rack bar I64 toward the left and to swing the gear segment I63 and associated parts in a counterclockwise direction (Fig. 5)

The sleeve I60 is also provided with a radially extending arm I which supports a stud I16 at its outer end. The stud I16 supports a pair of pawls I11 and I18 which are arranged to engage a ratchet wheel I19 which is in turn rigidly fixed to rotate with the hand wheel 59. The hand wheel 59 is keyed to a reduced end portion of the shaft.

The pawls I11 and I18 vary in length by an amount substantially equal to one-half of a ratchet tooth. The pawls I11 and I18 are normally held in an operating position by means of \4 a spring-pressed plunger I80 which engages notches in the stud I16 and may be moved into an inoperative position by means of a manually operable lever II. The lever I8I is fastened to the pawl I 11. The pawl I 11 is provided with a clearance hole I82. A pin I83 is fixed to the pawl I18 and passes through the clearance hole I82 so that when the pawl I11 is swung to and from an operating position by means of the lever I8l, the pawl I18 will also be moved by means of the pin I03. It will be readily apparent from the foregoing disclosure that when the pawl carrying stud I16 and pawls I11 and I18 are oscillated in either direction by the spring I68 or by the admission of fiuid under pressure into the cylinder chamber I12, the pawls I11 and I18 will be caused to oscillate, either riding idly over the ratchet wheel I19 when moved in a clockwise and piston rod I65 toward the left (Fig. 5) which serves to swing the gear segment I63 in a counterclockwise direction (Fig. 5) which in turn oscillates the pawls I11 and I18 and the ratchet wheel I19 and feed wheel 59 also in a counterclockwise direction (Figs. 1 and 9) to turn the feed screw 53 and thereby advance the diamond 5| toward the wheel axis so that upon its next traversing stroke across the wheels, it will true a predetermined amount oil the wheels. The engagement of the end of the piston rod I65 with a stop screw I84 serves to limit the movement of the pawls I11 and I18 in a counterclockwise direction.

Thespring I68 serves to return the piston rod I65 toward the right (Fig. 5) to return the feeding mechanism parts, namely the pawls I11 and I18, to their initial position ready for the next feeding movement. In order to adjust the extent of infeeding movement, a stop device is provided for limiting the movement of the pawls I11 and I18 in their idle movements in a clockwise direction (Figs. 1 and 9). An arcuate slideway I85 is fixedly secured to the casing I10 and serves as a support for an arcuate slide I 86 which is provided with a stop abutment I81. By adjusting the position of the arcuate slide I86, the position of the abutment I81 may be varied as desired to regulate the extent of movement of the pawls I11 and I18 in their idle stroke over the teeth of the ratchet wheel I19. To facilitate adjustment of the abutment I81, the periphery of the arcuate slideway I85 is formed as a worm segment I88. A

. a pivot to throw the worm I89 out of mesh with the worm segment I88 and the slide I86 may then be adjusted on its arcuate slideway I85 and the worm I89 again thrown into mesh with the worm segment I88. The worm I89 is rotatably supa graduated scale is provided on a collar I 93 carported in the casing I90 in bearings and is supported so that it may be rotated manually pre cisely to adjust the position of the abutment I81 by means of a knob I92 which is mounted on the outer end of theshaft for the worm I89. To facilitate adjustment of the abutment .I81,

ried by the knob I92 and a fixed index point I94 is provided on the casing. I90 so that the abutment I81 may be precisely adjusted to reposition the arm I15 as desired. It will be readily apparent from the foregoing disclosure that when the pawls I11 and I18 are moved idly over the ratchet wheel I19 in a clockwise direction (Figs. 1 and 9) by means of the released compression of the spring I68, the movement will continue until an abutment I95 carried by the arm I15 engagcsthe adjustably fixed abutment I81 which stops the movement of the piston I66 toward the right (Fig. 5) under the influence of the spring I68. The pawls I11 and I 18 are then in position for the next infeeding movement. To facilitateholding the knob I92 in its adjusted position, a springpressed plunger 200 is carried by the frame I90 and is arranged to engage one of a plurality of holes or depressions 20I withinthe portion I93 of the knob I92.

The fluid pressure system is preferably arranged so that fluid under pressure may be admitted through the pipe I'I I into the cylinder chamber I12 to actuate the feeding mechanism to advance the truingtool 50 at each end of its.

as illustrated in the drawings, the right-hand end of the valve 61 is arranged so as to control the admission of fluid to the feed cylinder I61 at each end of the tool stroke so as to advance thediamond 5I toward the wheel axis before the tool starts its traversing movement in the reverse direction. The right-hand end of the valve stem 15 is provided with a central aperture205. When the valve stem 15 is moved toward the right to reverse the direction of fluid under pressure to the traverse cylinder 60, the ports 206 within the piston 18 pass a port 201 inthe valve sleeve and fluid under pressure from the pipe or passage 66a passes through the port 201, the .port 206, into the central aperture 205 within the valve stem 15, and out through apertures 208 and a port 209, into the pipe I1I into the feed cylinder chamber I12 to move the piston I66 toward the left (Fig. 5) against the compression of the spring I68 to move the feed mechanism part in a counterclockwise direction (Figs. 1, 5 and 9).

, The valve stem 15 inreversing moves so that the port 206;. in the valve piston passes by the port 201. After the port 206 passes the ports 201 in thevalve sleeves, the piston 18 cuts off fluid under pressure from the feed mechanism and when the valve reaches its extreme righthand position, fluid under pressure from pipe or passage 66a enters the valve chamber 85 to admit fluid under pressure to the pipe or passage 84 to start the tool traverse toward the left. In the position of the valve as illustrated in Fig. 5, the released compression of the spring I 68' exhausts fluid from. the cylinder chamber I12 through the pipe I1I which passes through the'port 209 and ports 208 in the valve stem 15 into the central aperture 205 and exhausts out through ports 2I0 in the valve stem, into'a pipe or passage 2 which conveys it to the reservoir 63. 2

It will be readily apparent that each time the valve stem 15 is moved either toward the right or toward the left, the ports 206 within the valve piston 18 will coincide with the poit 201 in the valve sleeve so that fluid under pressure from the pipe or passage 66a will be admitted to the feed -cylinder chamber I12 to actuate the feed pawls I11 and I18 which in turn serve to turn the ratchet wheel I19 and the feed wheel 59 to advance the truing tool a predetermined distance toward the wheel axis at each end of the reciprocatory stroke of the truing tool50.

The operation of this improved truing apparatus will be readily apparent from the foregoing disclosure. Assuming all of the parts have been previously adjusted, that is, the dogs I05 and I06 for length of stroke and the stop I81 for the amount of feed, the operation of the mechanism is initiated by the operator swinging the control lever I32 in a clockwise direction (Fig. 5) to shift the control valve 61 into its reverse position. During this movement, fluid passes through to the feed cylinder 60 to advance the truing tool 50 a predetermined amount before fluid is admitted through the pipe 84 to start the traverse of the slide 3| and diamond 5I toward the left (Figs. 1 and 5). The diamond 5| traverses first at a rapid rate with fluid exhausting through the valve 90 which is controlled by the cam 98. As the truing tool 50 approaches the side of the wheel I2, the released compression of the spring 96 cooperating with the cam 98 serves to close the valve 90 and thereafter fluid exhausts through the adjustable needle vvalve 99 into the reservoir 63 to traverse the truing tool 50 at a truing speed. During this movement the gear I56 rolling on the stationary rack I rotates the cam. I50 so that when the truing tool 50 engages the periphery of the wheel I2, the follower I54 will be in engagement with a concentric portion on the cam I50 so that there is no vertical movement of the truing tool 50 as it passes across the periphery of the wheel I2.

When the tool 50 has traversed across the face of the wheel I2, the continued longitudinal movement of the slide 3| rotates the cam I50 through a further extent to drop the truing tool 50 to position it for truing the wheel I3 to a second predetermined diameter and the follower I54 engages a second concentric portion on the cam I50 during the time the truing tool 50 is traversing across the periphery thereof. During this pass of the truing tool across the periphery of the two spaced grinding wheels I2 and I3, the speed of movement of the slide 3| is governed by the contour of the cam 98 which is arranged so that when the truing tool is out of engagement with the wheel peripheries, the slide 3I will travel at a rapid rate and when the tool is in truing engagement with either of the grinding wheels, the truing tool will be traversed at a predetermined slow truing. speed.

The movement of the slide 3| toward the left continues until the dog I06 engages the reversing lever I08 which rocks the shaft I09, first taking up lost motion between the shaft I08 and the lever H2 and then causing the arrow-pointed spring-pressed plunger I28 to ride over the roller I25. After the high point of the arrow I28 rides by the periphery of the roller I29, the released compression of the spring quickly snaps the reverse valve 15 into its reverse position, During the shift-over of the reverse valve, fluid under pressure from the pipe or passage 66a passes through the valve port 201 above described into the pipe or passage I H to actuate the tool feeding mechanism to advance the truing tool 50 ready for the next traversing movement. The diamond 5| will continue to traverse automatically until the lever I32 is raised to the dotted position l32w when the slide 3| is moving in a direction toward the right which serves to throw the reversing lever 108 out of the path of the dog I05 to allow the truing tool 50 to move to its extreme right-hand or inoperative position (Fig. 1) In this position of the parts, the piston 6| abuts against the cylinder head and the truing tool 50 and associated parts remain in this position so that the truing tool is out of engagement with the grinding wheels l2 and I3 during the grinding operation.

It will thus be seen that there has been probe made in the embodiment above set'forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A lever stop mechanism for machine tools comprising an adjustable stop abutment positively to limit a movable machine part, an arcuate slideway therefor, a worm gear segment on said slideway, a casing pivotally supported on said slide, a worm rotatably supported on said casing and arranged to mesh with said gear segment, and a manually operable knob to actuate said worm. to adjust the position of said stop abutment, said casing and worm being arranged so that the gear may be swung out of mesh with said segment to facilitate rapid repositioning of said stop abutment.

2. A lever stop mechanism for machine tools comprising an adjustable stop abutment positively to limit the movement of a machine control member, an arcuate slideway therefor, a

worm gear segment on said slideway, a casing pivotally mounted on said slide, a worm rotatably supported in said casing and arranged to mesh with said gear segment, and a manually operable knob to rotate said worm to precisely adjust the position of said abutment, said worm being arranged normally to mesh with said gear segment under the influence of gravity and said casing being arranged so that the worm may be swung out of mesh with said gear segment to facilitate rapid adjustment of the stop abutment.

' WALLACE H. WOOD. 

